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package Perl::Critic::Policy::TooMuchCode::ProhibitUnnecessaryUTF8Pragma;
# ABSTRACT: "use utf8" is probably not needed if all characters in the source code are in 7bit ASCII range.
use strict;
use warnings;
use Perl::Critic::Utils;
use parent 'Perl::Critic::Policy';
sub default_themes       { return qw( bugs maintenance )     }
sub applies_to           { return 'PPI::Document' }
#---------------------------------------------------------------------------
sub violates {
    my ( $self, $elem, $doc ) = @_;
    my $use_utf8_statements = $elem->find(
        sub {
            my $st = $_[1];
            $st->isa('PPI::Statement::Include') && $st->schild(0) eq 'use' && $st->schild(1) eq 'utf8';
        }
    );
    return unless $use_utf8_statements;
    my $chars_outside_ascii_range = 0;
    for (my $tok = $elem->first_token; $tok; $tok = $tok->next_token) {
        next unless $tok->significant;
        my $src = $tok->content;
        utf8::decode($src);
        my @c = split /\s+/, $src;
        for (my $i = 0; $i < @c; $i++) {
            if (ord($c[$i]) > 127) {
                $chars_outside_ascii_range++;
            }
        }
        last if $chars_outside_ascii_range;
    }
    unless ($chars_outside_ascii_range) {
        return $self->violation(
            "'use utf8;' seems to be unnecessary",
            'All characters in the source code are within ASCII range.',
            $use_utf8_statements->[0],
        );
    }
    return;
}
1;
HideShow 14 lines of Pod
=encoding utf-8
=head1 NAME
TooMuchCode::ProhibitUnusedImport -- Find 'use utf8' statement that produces (almost) no effect.
=head1 DESCRIPTION
The utf8 pragma is used to declare that the source code itself can be decoded by utf-8 encoding rule
as a sequence of characters. What this means is that all the characters in the code are within the
ASCII range.
=cut